Radiosonde Requirements.pdf

SALIENT CHARACTERISTICS – REQUIREMENTS

FOR METEOROLOGICAL RADIOSONDES

MODELS REQUIRED:

- Vaisala RS41-SG: Standard radiosonde (See attached data sheet)

- Vaisala RS41-SGM: Secure radiosonde with encryption (See attached data sheet)

- Vaisala RS41-SGE: Eco-friendly radiosonde cover (See attached data sheet)

Radiosonde RS41-SG

Features

• Superior PTU measurement performance

• Automated ground check

• Robust and easy-to-use design with informative LEDs

• GNSS for reliable wind data availability as well as height and pressure calculation

• Stable narrow band transmission complies with ETSI standard

EN 302 054

• Unwinder pin for consistent sensor boom positioning

Temperature and humidity sensors Vaisala Radiosonde RS41 temperature sensor is stable, using linear resistive platinum technology. The small size of the sensor results in low solar radiation error and guarantees fast response. It also effectively protects against evaporating cooling, the phenomenon occasionally encountered when a radiosonde emerges from a cloud top.

RS41 humidity sensor integrates humidity and temperature sensing elements to provide unique features.

Preflight automatic recondition of the humidity sensor effectively removes chemical contaminants and ensures excellent humidity measurement accuracy. The integrated temperature sensor compensates the effects of solar radiation in real time resulting in very precise measurement. The sensor heating function enables an active and effective deicing method at freezing conditions during the flight. The humidity sensor responds quickly to detect fine structures of the atmosphere.

RS41 ground check Automated ground check before flight includes temperature check, humidity sensor recondition, humidity check, and setting radiosonde parameters.

Wind data, height, and pressure Wind is derived from velocity based on satellite carrier frequency changes.

Height and pressure are based on satellite ranging codes, either combined with differential corrections from the ground system, or using multiple GNSS systems which enhance accuracy and mitigate GNSS interference. Pressure calculation is supplemented with temperature and humidity data.

Data transmission RS41 has proven data transmission from radiosonde to receiver up to 350 km.

Data availability during a sounding is guaranteed with digital error correction code transmission and telemetry errors are always detected. Due to narrower band transmission, more channels are available in the meteorological frequency band.

RS41 calibration RS41 temperature and humidity sensors are calibrated against the references that are traceable to SI standards and measurement uncertainties are estimated according to recommendations of Joint Committee for Guides in Metrology, 100:2008.

Unwinder With the unwinder the radiosonde sensor boom is automatically set in an ideal position for sounding. As the unwinder is separated from the radiosonde, you can prepare the balloon and unwinder in advance to streamline launch preparations.

Additional sensor connector RS41 has a serial interface for additional sensors, primarily to connect ozone interface to RS41. You can also connect other sensors with XDATA protocol. The data is transferred either directly or through ozone interface to a RS41 radiosonde and further to Vaisala sounding system.

Vaisala radiosondes are known for their accuracy, reliability, and ease of use.

Technical data

Measurements

Measurement cycle 1 s

Temperature sensor Type: Platinum resistor

Measurement range +60 ... −95 °C

Resolution 0.01 °C

Response time (63.2 %, 6 m/s flow, 1000 hPa)1) 0.5 s

Stability (1 year / 3 years) < 0.05 °C / < 0.1 °C

Accuracy:

Repeatability in calibration 0.1 °C

Combined uncertainty after ground preparation

Combined uncertainty in sounding < 16 km

Combined uncertainty in sounding > 16 km

0.2 °C

0.3 °C

0.4 °C

Reproducibility in sounding 2) > 100 hPa: 0.15 °C

< 100 hPa: 0.30 °C

Humidity sensor Type: Thin-film capacitor

Measurement range 0 to 100 %RH

Resolution 0.1 %RH

Response time: 6 m/s, 1000 hPa +20 °C: < 0.3 s

−40 °C: < 10 s

Accuracy:

Repeatability in calibration 2 %RH

Combined uncertainty after ground preparation 3 %RH

Combined uncertainty in sounding 4 %RH

Reproducibility in sounding 2) 2 %RH

Pressure Type: Calculated from GNSS

Measurement range From surface pressure to 3 hPa

Resolution 0.01 hPa

Accuracy:

Combined uncertainty / Reproducibility in sounding 2)

> 100 hPa: 1.0 hPa / 0.5 hPa

100-10 hPa: 0.3 hPa / 0.2 hPa

< 10 hPa: 0.04 hPa / 0.04 hPa

Geopotential height Type: Calculated from GNSS

Measurement range 3) From surface to 40 000 m

Resolution 0.1 gpm

Accuracy:

Combined uncertainty in sounding 10.0 gpm

Reproducibility in sounding 2) 6.0 gpm

Wind speed

Velocity measurement uncertainty 4) 0.15 m/s

Resolution 0.1 m/s

Maximum reported wind speed 3) 180 m/s

Wind direction

Directional measurement uncertainty 4) 2 deg

Resolution 0.1 deg

Wind direction range 0 to 360 deg

1) After applying time-lag correction, the effect to measurement uncertainty is negligible.

2) Standard deviation of differences in twin soundings, ascent rate above 3 m/s

3) In practice unlimited

4) Standard deviation of differences in twin soundings. Wind speed above 3 m/s for directional measurement uncertainty.

Telemetry

Transmitter type Synthesized

Frequency band 400.15 – 406 MHz

Tuning range 400.16 – 405.99 MHz

Maximum transmitting range Up to 350 km

Frequency stability, 90 % probability ±2 kHz

Deviation, peak-to-peak 4.8 kHz

RF compatibility According to EN 302 054

Output power (high-power mode) Min. 60 mW

Modulation GFSK

Data downlink 4800 bit/s

Frequency setting Wireless with ground check device

Authentication algorithm HMAC-SHA256 1)

1) Requires Vaisala Cirrus Sounding System MW51

GNSS receiver

GNSS systems GPS, Galileo 1), BeiDou 1)

Number of channels ≥ 48

Frequency 1575.42 MHz, L1 C/A code

Cold start acquisition time 35 s (nominal)

Reacquisition time 1 s (nominal)

Reporting resolution of lat, lon position values

1e-8°

1) Requires Vaisala Cirrus Sounding System MW51

Operational data

Power-up Wireless or with switch

Factory calibration Stored on Flash memory

Battery 2 pcs AA-size Lithium cells

Operating time > 240 min

Weight 80 g

Dimensions (for cover, without wire antenna)

Body (L × W × H): 155 × 63 × 46 mm

Sensor boom bent (L × W × H):

282 × 63 × 104 mm

Additional sensor support

Protocol support XDATA

Transfer rate Max. 200 bytes/s

Unwinder

Material of the string Non-UV treated polypropylene

Strength (pull) <115 N

Length of the string 55 m

Unwinding speed 0.35 m/s

Weight 25 g

The performance data is expressed with 2-sigma confidence level (k=2), unless otherwise specified. For humidity, the performance data is valid T > -60 °C.

Published by Vaisala | B211321EN-L © Vaisala Oyj 2024

All rights reserved. Any logos and/or product names are trademarks of Vaisala or its individual partners. Any reproduction, transfer, distribution or storage of information contained in this document is strictly prohibited.

All specifications — technical included — are subject to change without notice.

Radiosonde RS41-SGM

• Improved security thanks to radio silence and encryption

• Superior PTU measurement performance

• Automated ground check

• Robust and easy-to-use design

• GNSS for reliable wind data availability as well as height and pressure calculation

• Stable narrow band transmission complies with ETSI standard

EN 302 054

• Unwinder for consistent sensor boom positioning

Improved security Vaisala Radiosonde RS41-SGM features radio silence (patent EP2689279 and US

9,972,198, Method for launching and a radiosonde), which improves security of defense operations. Radiosonde transmission does not reveal the balloon launch location because the radiosonde transmitter is not switched on until a specified height or time from launch has been reached. Data is recorded also during the radio silence and, when the radio silence ends, transmitted to the ground equipment. Transmitted data is also encrypted.

Temperature and humidity sensors Vaisala Radiosonde RS41 temperature sensor is stable, using linear resistive platinum technology. The small size of the sensor results in low solar radiation error and guarantees fast response. It also effectively protects against evaporating cooling, the phenomenon occasionally encountered when a radiosonde emerges from a cloud top.

RS41 humidity sensor integrates humidity and temperature sensing elements to provide unique features.

Preflight automatic recondition of the humidity sensor effectively removes chemical contaminants and ensures excellent humidity measurement accuracy. The integrated temperature sensor compensates the effects of solar radiation in real time resulting in very precise measurement. The sensor heating function enables an active and effective deicing method at freezing conditions during the flight. The humidity sensor responds quickly to detect fine structures of the atmosphere.

RS41 ground check Automated ground check before flight includes temperature check, humidity sensor recondition, humidity check, and setting radiosonde parameters.

Short range wireless communication link with range around 4 cm is used in ground check devices for data transfer during the ground check.

Wind data, height, and pressure Wind is derived from velocity based on satellite carrier frequency changes.

Height and pressure are based on satellite ranging codes, either combined with differential corrections from the ground system, or using multiple GNSS systems which enhance accuracy and mitigate GNSS interference. Pressure calculation is supplemented with temperature and humidity data.

RS41 calibration RS41 temperature and humidity sensors are calibrated against references that are traceable to SI standards, and measurement uncertainties are estimated according to recommendations of Joint Committee for Guides in Metrology, 100:2008.

Operational benefits RS41-SGM has been designed for mobile use in the field. In its transport package, it has been tested to comply with MIL-

STD-810G for transit drop, vibration, low and high temperature, and low pressure.

Vaisala radiosondes are known for their accuracy, reliability, and ease of use.

Measurement cycle 1 s

Temperature sensor Type: Platinum resistor

Measurement range +60 ... −95 °C

Resolution 0.01 °C

Response time (63.2 %, 6 m/s flow, 1000 hPa)1) 0.5 s

Stability (1 year / 3 years) < 0.05 °C / < 0.1 °C

Accuracy:

Repeatability in calibration 0.1 °C

Combined uncertainty after ground preparation

Combined uncertainty in sounding < 16 km

Combined uncertainty in sounding > 16 km

0.2 °C

0.3 °C

0.4 °C

Reproducibility in sounding 2) > 100 hPa: 0.15 °C

< 100 hPa: 0.30 °C

Humidity sensor Type: Thin-film capacitor

Measurement range 0 to 100 %RH

Resolution 0.1 %RH

Response time: 6 m/s, 1000 hPa +20 °C: < 0.3 s

−40 °C: < 10 s

Accuracy:

Repeatability in calibration 2 %RH

Combined uncertainty after ground preparation 3 %RH

Combined uncertainty in sounding 4 %RH

Reproducibility in sounding 2) 2 %RH

Pressure Type: Calculated from GNSS

Measurement range From surface pressure to 3 hPa

Resolution 0.01 hPa

Accuracy:

Combined uncertainty / Reproducibility in sounding 2)

> 100 hPa: 1.0 hPa / 0.5 hPa

100-10 hPa: 0.3 hPa / 0.2 hPa

< 10 hPa: 0.04 hPa / 0.04 hPa

Geopotential height Type: Calculated from GNSS

Measurement range 3) From surface to 40 000 m

Resolution 0.1 gpm

Accuracy:

Combined uncertainty in sounding 10.0 gpm

Reproducibility in sounding 2) 6.0 gpm

Wind speed

Velocity measurement uncertainty 4) 0.15 m/s

Resolution 0.1 m/s

Maximum reported wind speed 3) 180 m/s

Wind direction

Directional measurement uncertainty 4) 2 deg

Resolution 0.1 deg

Wind direction range 0 to 360 deg

1) After applying time-lag correction, the effect to measurement uncertainty is negligible.

2) Standard deviation of differences in twin soundings, ascent rate above 3 m/s

3) In practice unlimited

4) Standard deviation of differences in twin soundings. Wind speed above 3 m/s for directional measurement uncertainty.

Telemetry

Transmitter type Synthesized

Tuning range 400.16- 405.99 MHz

Frequency band 400.15 - 406 MHz

Frequency stability, 90 % probability ± 2 kHz

Deviation, peak-to-peak 4.8 kHz

RF compatibility According to EN 302 054

Output power (high-power mode) Min. 60 mW

Modulation GFSK

Data downlink 4800 bit/s

Frequency setting Wireless with MWH322/RI41

Radio silence Up to 5 km or 20 min

Data encryption (stream cipher) 128-bit key

Transmitter termination User-selectable based on timer or height

Authentication algorithm HMAC-SHA256 1)

1) Requires Vaisala Cirrus Sounding System MW51

GNSS receiver

GNSS systems GPS, Galileo 1), BeiDou 1)

Number of channels ≥ 48

Frequency 1575.42 MHz, L1 C/A code

Cold start acquisition time 35 s (nominal)

Reacquisition time 1 s (nominal)

Reporting resolution of lat, lon position values

1e-8°

1) Requires Vaisala Cirrus Sounding System MW51

Operational data

Power-up Wireless or with switch

Factory calibration Stored on Flash memory

Battery 2 pcs AA-size Lithium cells

Operating time > 240 min

Weight 80 g

Dimensions (for cover, without wire antenna)

Body (L x W x H): 155 x 63 x 46 mm

Sensor boom bent (L x W x H):

282 x 63 x 104 mm

Environmental tests (transit drop, vibration, low and high temperature and low pressure)

MIL-STD-810G

Unwinder

Material of the string Non-UV treated polypropylene

Strength (pull) <115 N

Length of the string 55 m

Unwinding speed 0.35 m/s

Weight 25 g

The performance data is expressed with 2-sigma confidence level (k=2), unless otherwise specified. For humidity, the performance data is valid T > -60 °C.

Published by Vaisala | B211448EN-J © Vaisala Oyj 2024

All rights reserved. Any logos and/or product names are trademarks of Vaisala or its individual partners. Any reproduction, transfer, distribution or storage of information contained in this document is strictly prohibited.

All specifications — technical included — are subject to change without notice.

Radiosonde RS41-SGE with BioCover

• Superior PTU measurement performance

• Automated ground check

• Robust and easy to use design with informative LEDs

• Biodegradable and microplastic-free Vaisala BioCover

• GPS for continuous wind data availability as well as height and pressure calculation

• Stable narrow band transmission complies with ETSI standard

EN 302 054

• Unwinder pin for consistent sensor boom positioning

Temperature and humidity sensors

Vaisala Radiosonde RS41 temperature sensor is stable, using linear resistive platinum technology. The small size of the sensor results in low solar radiation error and guarantees fast response. It also incorporates effective protection against evaporating cooling, the phenomenon occasionally encountered when a radiosonde emerges from a cloud top.

RS41 humidity sensor integrates humidity and temperature sensing elements to provide unique features.

Preflight automatic recondition of the humidity sensor effectively removes chemical contaminants and ensures excellent humidity measurement accuracy. Integrated temperature sensor is used for compensating the effects of solar radiation in real time resulting in very precise measurement. The sensor heating function enables an active and effective deicing method when a radiosonde is flying through layers with freezing conditions. The humidity sensor is very accurate throughout the whole measurement range and has fast response to detect fine structures of the atmosphere.

Vaisala BioCover

The cover and insulation of Vaisala

BioCover™ are based on natural fibres, starch, and some additives, all being natural, bio-based, biodegradable, and microplastic-free. This material reduces the environmental impact of the radiosonde after service.

RS41 ground check

RS41 ground check includes several functional checks: temperature check, humidity sensor recondition, humidity check, and setting radiosonde parameters. Ground check is performed before flight on a radiosonde placed on the Ground Check Device RI41, which is conveniently operated with sounding software.

Wind data, height and pressure

Wind, height and pressure are derived from velocity and location measurements of the RS41 GPS receiver.

Height and pressure are calculated from satellite ranging codes, combined with differential corrections from the sounding software. Pressure calculation also uses temperature and humidity from the radiosonde. Wind is calculated independently based on satellite carrier frequency changes.

Data transmission

RS41-SGE has proven data transmission from radiosonde to receiver up to

350 km. This is sufficient for any sounding operations. Data availability during a sounding is guaranteed with digital error correction code transmission and telemetry errors are always detected. Due to narrower band transmission, more channels are available in the meteorological frequency band.

RS41 calibration

RS41 temperature and humidity sensors are calibrated against the references that are traceable to SI standards and measurement uncertainties are estimated according to recommendations of Joint Committee for Guides in Metrology, 100:2008.

Unwinder with BioTwine

The Vaisala BioTwine™ is a cellulose-based material being natural, bio-based, biodegradable, and microplastic-free. It degrades and loses its strength fast after service. With the unwinder pin, the radiosonde sensor boom is automatically set in an ideal position for sounding. As the unwinder is separated from the radiosonde, you can prepare the balloon and unwinder in advance to streamline launch preparations.

Measurement cycle 1 s

Temperature sensor Type: Platinum resistor

Measurement range +60 °C to −100 °C

Resolution 0.01 °C

Response time (63.2 %, 6 m/s flow, 1000 hPa) 1) 0.5 s

Stability (1 year / 3 years) < 0.05 °C / < 0.1 °C

Accuracy:

Repeatability in calibration 0.1 °C

Combined uncertainty after ground preparation

Combined uncertainty in sounding < 16 km

Combined uncertainty in sounding > 16 km

0.2 °C

0.3 °C

0.4 °C

Reproducibility in sounding 2) > 100 hPa: 0.15 °C

< 100 hPa: 0.30 °C

Humidity sensor Type: Thin-film capacitor

Measurement range 0 to 100 %RH

Resolution 0.1 %RH

Response time 6 m/s, 1000 hPa +20 °C: < 0.3 s

−40 °C: < 10 s

Accuracy:

Repeatability in calibration 2 %RH

Combined uncertainty after ground preparation 3 %RH

Combined uncertainty in sounding 4 %RH

Reproducibility in sounding 2) 2 %RH

Pressure Type: Calculated from GPS

Measurement range From surface pressure to 3 hPa

Resolution 0.01 hPa

Accuracy:

Combined uncertainty / Reproducibility in sounding 2)

> 100 hPa: 1.0 hPa / 0.5 hPa

100-10 hPa: 0.3 hPa / 0.2 hPa

< 10 hPa: 0.04 hPa / 0.04 hPa

Geopotential height Type: Calculated from GPS

Measurement range 3) From surface to 40 000 m

Resolution 0.1 gpm

Accuracy:

Combined uncertainty in sounding 10.0 gpm

Reproducibility in sounding 2) 6.0 gpm

Wind speed

Velocity measurement uncertainty 4) 0.15 m/s

Resolution 0.1 m/s

Maximum reported wind speed 3) 180 m/s

Wind direction

Directional measurement uncertainty 4) 2 deg

Resolution 0.1 deg

Wind direction range 0 to 360 deg

1) After applying time-lag correction, the effect to measurement uncertainty is negligible.

2) Standard deviation of differences in twin soundings, ascent rate above 3 m/s

3) In practice unlimited

4) Standard deviation of differences in twin soundings. Wind speed above 3 m/s for directional measurement uncertainty.

Telemetry

Transmitter type Synthesized

Frequency band 400.15 – 406 MHz

Tuning range 400.16 – 405.99 MHz

Maximum transmitting range Up to 350 km

Frequency stability, 90 % probability ±2 kHz

Deviation, peak-to-peak 4.8 kHz

Emission bandwidth According to EN 302 054

Output power (high-power mode) Min. 60 mW

Sideband radiation According to EN 302 054

Modulation GFSK

Data downlink 4800 bit/s

Frequency setting Wireless with ground check device

GPS receiver (SA Off, PDOP<4)

Number of channels ≥ 48

Frequency 1575.42 mHz, L1 C/A code

Cold start acquisition time 35 s (nominal)

Reacquisition time 1 s (nominal)

Correction Differential

Reporting resolution of lat, lon position values

1e-8°

Operational data

Power-up Wireless with ground check device or with switch

Factory calibration Stored on Flash memory

Battery 2 pcs AA-size Lithium cells

Operating time > 240 min

Weight 90 g

Dimensions 1) Body (L × W × H): 157 × 59 × 50 mm

Sensor boom bent (L × W × H):

237 × 59 × 105 mm

1) For cover; without wire antenna

Unwinder

Material of the string Cellulose-based

Strength (pull) < 95 N

Length of the string 55 m

Unwinding speed 0.26 m/s

Weight 31 g

The performance data is expressed with 2-sigma confidence level (k=2), unless otherwise explicitly specified.

For humidity, the performance data is valid T > -60 °C.

Published by Vaisala | B212709EN-A © Vaisala 2023

All rights reserved. Any logos and/or product names are trademarks of Vaisala or its individual partners.

Any reproduction, transfer, distribution or storage of information contained in this document is strictly prohibited. All specifications — technical included — are subject to change without notice.

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